The squealing has nothing to do with a camber kit in this case. Lowering the car will result in increased negative camber, but this increased negative camber actually increases cornering grip because the increased negative camber puts more on the contact patch on the ground during corner loading. That's why road racers and autocrossers will have lots more negative camber than stock.

So it's probably your tires.

Have you had alignment that told you what your camber is at right now?

If not, post up some decent pics and try to show what the camber looks like.